Folding Behavior of Polypeptides.A Monte Carlo Study of Simplified Models

摘要

A simple model of polypeptide chains was designed and studied.The chains were constructed on a flexible [310] lattice and consisted of united atoms located at the position of alpha carbons.Each united atom represented amino acid residues of two kinds:hydrophilic and hydrophobic.The sequence of the residues was assumed to be characteristic for alpha-and beta-type of proteins.The force field used consisted of the long-range contact potential between polymer segments,the short range repulsion,and the local potential preferring conformational states characteristic for alpha-helices and beta-strands.The Monte Carlo simulations of this model were carried out using the replica exchange technique coupled with the histogram method.The influence of temperature and the local potential on the size and internal structure of collapsed low temperature chains were studied.Thermodynamics of these systems consisting mainly of alpha and beta secondary structures were determined.The properties of the coil-to-globule transition were presented and compared with other theoretical predictions and simulation results.